1. Field of the Invention
This invention relates generally to heat exchange of an electrical article and more particularly to cooling a module containing a plurality of integrated circuit chips.
2. Description of the Prior Art
The temperature of integrated circuit chips must be kept below specified limits to ensure proper function, reliability and useful life. The trend in integrated circuit technology is to pack more circuits per chip which increases the heat generation per chip. Also, system designers are mounting chips closer together to minimize propagation delays in the interconnections. These trends and designs have increased heat flux, i.e. power per unit area, and caused a need for new cooling techniques.
In the conduction cooling of heat producing elements, a conductive heat transfer medium (a solid) is placed into contact with a heat producing element. The medium either has, or contacts another element which has, a greater surface area relative to the heat producing element so that heat is more easily dissipated from the greater surface area. To enhance heat dissipation from surface areas, a fluid is often used as a heat transfer medium by being moved over the heat dissipating surface area to "carry away" heat by convection. From the foregoing it becomes quite clear that heat transfer is enhanced when there is greater surface contact between a heat producing element and a heat transfer medium.
The development of multichip thermal conduction modules to enhance the cooling of concentrations of chips resulted in various conduction cooling techniques including a plurality of resiliently urged pistons each contacting a chip and providing a thermal path to a portion of the module housing which is convection cooled by a fluid coolant.
This technique was further enhanced by encapsulating the pistons in Helium gas to promote conduction cooling. Also, coolants such as air, water and fluorocarbons have been pumped through the housings.
Such pistons limit heat transfer regardless of piston geometry dxe to the rigidity of the piston. For example, if the piston has a curved contact surface then limited point contact with the relatively planar chip surface results in reduced heat transfer. Where the piston also has a relatively planar contact surface, the piston and chip contact surfaces must be in substantial alignment to avoid point contact.
A major problem of present day liquid cooling systems is the need for external plumbing to be connected to processor cabinets, and the like, the need for a special fluid pumping system, and the difficulties involved in repairing damaged boards because of such fluid connections.
The foregoing illustrates limitations of the known prior art. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations as set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.